Television coding system



July 3, 1956 M. G. PAWLEY ET AL 2,753,393

TELEVISION CODING SYSTEM Filed Aug. 51, 1951 2 Sheets-Sheet 1 INVENTOR$@rwz afazrley JMZJZ. .'wizg.

JV W P A'TTORNEY y 1956 M. a. PAWLEY ET AL 4 2,753,393

TELEVISION CODING SYSTEM Filed Aug. 31, 1951 2 Sheets-Sheet 2 INVENTORS1y raa ij az ley emZflu'aofig,

\ a ATTORNEY United States Patent TELEVISION CODING SYSTEM Myron G.Pawley, Alexandria, Va., and Jacob M. Sacks, Silver Spring, Md.,assignors, by mesne assignments, of one-third to Lena Becker Paris,exeeutrix of Israel Richard Paris, deceased Application August 31, 1951,Serial No. 244,622

8 Claims. (Cl. 1785.1)

The present invention relates generally to coding systems and is moreparticularly concerned with coding systerns which are designed to varyperiodically. The object of this invention is to provide such a systemwith simple and facile means for varying the code as desired.

The present invention is designed primarily for use and cooperation withsubscribers television systems, such as the system shown in ourco-pending application, Ser. No. 230,618, filed June 8, 1951, and thesystem shown therein is hereby embodied in the present application andis made a part hereof. In the system shown in this copendingapplication, the televised image is coded at the broadcasting stationand the code is varied periodically, as from day to day or from programto program. Each subscribers television set is provided with acorresponding code system which also needs to be pre-set in agreementwith the code employed at the broadcasting station. For this purpose thecoding unit at the subscribers receiver is provided with a group oftwo-position switches which need to be set in one position or the otherin agreement with a key code which the subscriber has to obtain from thebroadcasting station for each performance. The present invention aims toprovide a ready means whereby the subscriber may set or adjust the groupof switches so that the coding system generates the desired code.

In addition, the preesnt invention aims to render the coding systemsubstantially tamper-proof. For these purposes the casing which housesthe coding system is provided with a chamber having a slot-like openingor entrance and which is designed to receive a code card which willbear, by punchings or the like, the key code for the specificperformance and for the specific receiver. Each of the group of switcheswhich determine the code has an operator which projects into the chamberfrom one face thereof, thereby normally maintaining the switches in apredetermined position. By the insertion of the code card into thechamber some of the switches are moved from the normal position to thesecond position in accordance with the key code for the desiredperformance and for the specific receiver and thereby the coding systemwill be set to generate the desired code.

Another feature of the present invention is that means are providedwhich make it possible for the machine to identify or recognize agenuine code card and will cooperate only with such genuine cards. Themeans for accomplishing this end includes a first part which is disposedor fixed in the casing and a second part carried by the code card whichrenders the first part effective to energize the code system.

It is contemplated that the code cards of the present invention shouldbe supplied to the subscriber for his future use and that these cardsshould be redeemable or exchangeable for other cards if the subscriberdoes not use the card. For this purpose, the chamber which receives acode card may be provided with means for mutilating the card orotherwise marking it to show that the card has been used and is notredeemable.

The organization and manner of operation in the present invention andfurther objects or advantages thereof will be best understood byreference to the following specification ad the accompanying drawings,it being understood that these serve to illustrate a preferredembodiment of the invention and that variations thereof falling withinthe scope of the appended claims will be apparent to persons skilled inthe art.

Iln the drawings, some of which are on an enlarged sca e:

Fig. 1 is a perspective of the coding unit embodying the presentinvention;

Fig. 2 is a view of one face of the code card receiving chamber taken online 22 of Fig. 1;

Fig. 3 is a view of the opposite face of the code card receiving chambertaken on line 3-3 of Fig. 1;

Fig. 4 is a view of one type of code card;

Fig. 5 is a wiring diagram of the identification system cooperating withthe card shown in Fig. 4;

Fig. 6 is a view of another type of code card;

Fig. 7 is a sectional view taken on line 7-7 in a system employing thecard of Fig. 6.

The housing 10 shown in Fig. 1 houses within it a coder unit or codingsystem of any suitable type such as the types shown and described in theabove co-pending application. It is thought unnecessary to describe thecoding system shown there for the manner in which the present inventioncooperates with the coding system can be fully described without anydiscussion of the coding system itself.

The cable 13 and multi-contact plug 14 is employed for connecting thecoding system housed in the housing 10 to the normal televisionreceiving apparatus 19 which is provided with a plug receivingreceptacle 15. When the plug 14 is inserted into the plug receivingreceptacle 15 the electrical connections between the coding system inthe housing 10 and the television receiver 19 are established as shownin the co-pending application. The switch 12 may connect a power sourceto the coding system.

The switches which need to be preset for each performance in accordancewith a key code in order to adjust the coding system to generate thedesired code are disposed in the housing or casing 10 and have theiroperating arms 21, which may be spring pressed, extend into the chamber17. The code cards which are employed in the present system have twopurposes which coperate to render the apparatus tamper-proof. One isthat each card carries a key code for a specific performance and theother is that the card carries devices which cooperate with other fixeddevices in the coder unit for introducing the delay line of the unitinto the scanning system of the television receiver. This other phase ofthe invention serves as a means by which the machine recognizes the cardas genuine and cooperates only with genuine cards.

The present application discloses two alternate systems for recognizingor identifying the card as genuine and which may be employed forswitching the delay line of the coding system into the scanning circuit;as to other phases of the present invention, such as the key code on thecode card and the manner in which the card cooperates with the arms 21and presets the switches, they remain the same on both types of codecards.

We shall therefore here first describe the parts of the code box andchamber 17 and the code card which cooperate to preset the switches, itbeing understood that this phase of the invention is common to bothforms of the invention.

The code card is designed to fit fairly snugly and to be forced intochamber 17 through its entrance 16. The

chamber and the card may preferably be keyed to each.

other so that the chamber will accept the card only when it is presentedin the correct position, as by providing As shown, the code zone of thecard may have code .punchings 24 which are designed to receive some ofthe switch operator arms 21 while the dotted and unpunched areas in thecode zone serveto depress the corresponding switch operators. Thus bythenumber and disposition of the code punchings '24 the desired switch armsare depressed and moved to their second position, while-the other armsenter the punchings and the switches remain in their normal biasedposition, in accordance with the key code for the performance.

As .another feature of the present invention, the code cards and theswitch arms cooperate to prevent the cards from being withdrawn .oncethe card has been inserted for operation. For this purpose the operatorheads 21 of the switches are wedge-shaped as shown at 25, these headsbeing spring pressed by springs 26 disposed in the switch casing 27 andagainst the collar 28. The upper sloping face of the head 21 permits thehead to be pressed inwardly against the spring 26 as the card isinserted until the upper edge of the card is flush with the entrance 16.At this point some of the operator heads 21 enter the punching 24 andthe lower faces of the heads 21 prevent the card from being retrieved.The leaf springs 30'may be carried by recesses in the face of thechamber 17 opposite the face carrying the switches, and press the codecard yieldingly against the wall of the chamber and 'keep the card inoperative position.

The card remains in the chamber throughout the coded program for whichthe key code on the card was particularly prepared. At the end of theprogram the subscriber turns off switch 12. The card may remain in thechamber until the user or subscriber later wishes to receive anothercoded performance for which he had previously obtained a code card. Atthis time the user inserts the new card against the previous cardpushing the same edgewise. This pressure of the upper edges of the codepunchings against the wedge shaped operator heads 21 will cause the sameto be depressed against the action of the springs and permit the card tobe pushed downward through the chamber 17 and into the receptacle 72where these used cards may be permitted to accumulate. If desired, thereceptacle may be locked against access by the subscriber and may beunlocked or unlatched by the service man when the coding system issubjected to periodic inspection, say once a'year. The service man thenremoves the cards. It may also be desirable to mutilate or otherwisemark the used cards to show clear evidence that it has been used. Forthis purpose, a scoring or rnutilatingdevice 32 may be mounted in theoutlet 33 of the chamber 17 so that as the used card is being forceddownward out of the chamber 17 it is being scored or otherwise marked ormutilated.

The mutilating device is particularly desirable for the purpose ofreadily distinguishing a used from an unused card, when and if thereceptacle is made accessible to the user.

The mutilating device is preferably so disposed that it scores ormutilates the portion of the card which bears the identification elementas the cell or diffraction grating morefully described below. Anidentification device as the replica difiraction grating would bemutilated so that it becomes useless.

If desired, latching pins operating in the manner described may beprovided independently of the switches and the code cards are thenprovided with suitable openings to'receive such latch pins. The switcharms may then have conventional rounded operating heads.

By means of the system as thus far described the subscriber may obtainfrom the telecasting station a group of code cards for a group ofprograms in the immediate future; The subscriber is free to use thecards or not or to use only a selected number of such cards. He may thenreturn the unused cards and be credited with V 4 them or exchange themfor other cards. The invention as thus far described is applicable toboth types of code cards and to both types of identification systems.

In the system, to which the present invention is particularlyapplicable, the delay line and other parts of the coding system areinterposed between the horizontal synchronizing generator and thehorizontal scanning generator which are conventional components oftelevision receivers. When the receiver is employed for receivinguncoded'programs these two components are connected directly to eachother and the coding system is by-passed. Before a coded program can bereceived this connection needs to be opened and the delay line andelectronic switch interposed.

To accomplish these ends the present invention provides circuit meansfor operating switches which normally by-pass the coding system andestablish a direct connection between the horizontal synchronizing pulsegenerator and the scanning generator but which operate when the card isinserted into the'chamber to interpose the delay line and the electronicswitch.

Broadly stated, the means for accomplishing this switching operationincludes two cooperating parts. One part is fixed'and disposed in thecoding unit casing and the other part is carried by the code card. Twoforms of this invention are shown herein. One such system is illustratedin Fig. 4 and Fig. 5 and the other system is shown in'Figs. 6 and 7. Inboth forms the switch operating system cooperates with the coding systemas thus far described to render the present coding system tamper-proofso that subscribers cannot tamper with the coding system so as to'renderthe same available to them without the use of code cards.-

' system carried by the code card. The'remainder of the switching systemis mounted in the code casing and is by itself inoperative to effect thedesired switching.

As will be observed from Fig. 5, the cell or cells 35 serve to supplypositive voltage to the grid 37 of the triode 38 which is normallybiased to cut-off. The application of the positive voltage from the cell35 renders the triode' 38 conductive and the relay 39 is energizedthereby operating the switch 40 to open its normally closed back contactand to close the normally open front contact." Thisserves to insert thedelay line into the circuit between the horizontal synchronizing pulsegenerator and the'scanning' generator and the coding system becomeseffective.

The inner wall of the chamber 17 is provided with a resilient termnal41which contacts the positive face of the cell and the opposed face of thechamber carries a similar contact 42 for grounding the negative terminalof the cell. v

In the system as thus far described the cell serves as an identificationfor the card to the machine and the coding unit will refuse to operateif a card is inserted which it does not recognize as genuine.

Figs. 6 and 7 show another identification system for switching thecoding system into the television receiver employing anotheridentification device. In this system electro-optical devices areemployed for energizing the relay 39 to operate the switch 40 aspreviously described. An optical device necessary to render theelectro-optical system operative is carried by the code card. Theelectrooptical system comprises a source of light and a photoelectriccell. When the photocell 51 receives light the current in the cell isamplified by the amplifier 52 and the relay 39 is energized to operatethe switch 40 to insert the delay line in the television receiverbetween horizontal synchronizing pulse generator and the scanof lightand the photocell are such that normally, that is without the code cardand its identification device in the chamber 17 no light reaches thephotocell. The code card carries for its identification device a lightrefracting element 63 which serves to direct the light to the photocelland thereby the circuit means including the relay 39 is energized andthe switch is operated or moved to its second position and maintained inthis position during the program or as long as switch 12 is closed andthe card remains in the chamber 17. Many types of refracting elementsmay be employed. In the preferred form a replica diffraction grating 63is employed to direct a beam of light upon the slit 54 in front of thephotocell 51. The replica diffraction grating 63 may be in the form of aseparate element that is inserted in a suitable opening in the card orit may be aflixed to one face of the card or the transparent cardmaterial itself may bear the grating as shown in Fig. 6. The source oflight is preferably monochromatic in the form of a slit 55. Thecollimator lens 56 directs parallel light rays upon and through thegrating and the lens 58 serves to focus or image the light issued fromthe grating 63 upon the slit S4 and the photocell 51. In the absence ofthe grating the light will be concentrated on the line 60 on the axis ofthe lens 58. With the grating a sharp line of light will fall on theslit 54. The distance from the slit S4 to the line 60 is determined bythe number of lines per inch in the grating or by the grating space.Thus the apparatus can be designed to be effective only wtih a gratinghaving a grating space falling within narrow limits.

The particular value of the use of the diffraction grating lies in thatthe subscriber will find it virtually impossible to duplicate it.

When the subscriber wishes to receive a coded program, he inserts thecode card into the chamber 17. Because of the bead 70 and groove 11 thecard can be inserted only when held in its correct position. As the cardis inserted some of the switch heads will enter the punchings in thecode zone. When the upper edge of the card is approximately flush withthe entrance 16 the switch operating heads will be selectively depressedor permitted to enter the punchings. These operator heads or, ifdesired, latches provided exclusively for this purpose, will hold thecard in position so that it cannot be withdrawn. The card energizes thecircuit means for operating the switch 40 to insert the code system intothe television set and at the same time the nature of the code generatedby the code system is established by the cooperation between theoperating heads 21 and the code punchings.

With switch 12 in the oif position no power is available to any of thedevices in the coder unit and as a consequence the switch 40 is in itsbiased position and in contact with its back contact. In this positionthe delay line is by-passed and the television receiver is available forreceiving uncoded conventional signals and is operable in its normal orconventional manner. For receiving coded signals the subscriber, inaddition to inserting the code card, also operates the switch 12 to itson position. This supplies power to all the devices in the casing 10.The relay 39 thereby becomes energized by virtue of the presence of thecode card in the chamber 17 and by the switch 12 in the closed position.

Thus this arrangement permits the normal operation of the receiver 19even when the code card is in the chamber 17 provided the power switch12 is open.

In the absence of the cell or the replica difiraction grating or somesimilar device carried by the card designed to cooperate with otherparts in the casing for rendering the coding unit effective, asubscriber may after obtaining a code card from the telecaster,duplicate the card and use the duplicate for receiving the coded programand return the original unmarked or unmutilated for credit. The presentinvention makes this method of bootlegging very difficult.

By means of the present invention, tamper-proof subscribers televisionsystems may be had in which the business relationship between thetelecaster and the subscriber are relatively simple.

Having described the invention we do not wish to be limited to theembodiments thereof described and claim as our invention the following:

1. In combination, a housing having a first chamber, a second chamberand an opening for access to the second chamber, a switch disposed inthe first chamber biased to one position, and means for moving saidswitch to a second position comprising a first part fixed in saidhousing and a second part carried by a card insertable into said secondchamber, said first part comprising a normally ineffective photoelectricsystem, and the second part comprising an optical device for renderingthe system eifective.

2. The combination of claim 1 in which the first part comprises a sourceof light and a photoelectric cell and the second part comprises a devicefor directing the light to the cell.

3. The combination of claim 2 in which the second part is a diflractiongrating.

4. In combination, a television receiver, a coding unit connectedtherewith, and a code setting and control systern for said coding unitfor enabling intelligible reception of a subscription television programhaving a coded unintelligible component, said code setting and controlsystem comprising a sealed housing, a master switch wholly contained insaid housing and inaccessible from the outside thereof for rendering thecoding unit selectively operative and inoperative, said housing having aslot opening therein, a plurality of code switch operators accessible insaid slot, a key code card adapted for reception in said slot and toactivate selected code switch operators, said card having authenticatingmeans embedded thereon, sensing means in said slot for detecting thepresence of said authenticating means, and means responsive to saidsensing means upon detection of said authenticating means to operatesaid master switch for rendering said code unit operative.

5. The combination set forth in claim 4, wherein said sensing meanscomprises a photoelectric system, and said authenticating meanscomprises a light modifying means.

6. The combination set forth in claim 4, wherein said sensing meanscomprises a light source and photoelectric cell, and said authenticatingmeans comprises a means for altering the path of light from said lightsource.

7. The combination set forth in claim 4, wherein said authenticatingmeans comprises a voltage source.

8. The combination set forth in claim 4, wherein said sensing meansincludes a means responsive to applied voltage, and said authenticatingmeans comprises a means for altering the voltage applied to said sensingmeans.

References Cited in the file of this patent UNITED STATES PATENTS2,251,525 Rosenthal Aug. 5, 1941 2,488,207 Lea Nov. 15, 1949 2,501,274Hamilton Mar. 21, 1950 2,561,752 Perdijon July 24, 1951

